An Emerging Solidarity: Worker Cooperatives, Unions, and the New Union Cooperative Model in the United States by Rob Witherell
https://portside.org/2014-04-12/emerging-solidarity-worker-cooperatives-unions-and-new-union-cooperative-model-united
Last May, ACTRAV and the ILO cooperative branch held a seminar on the topic of relations between trade unions and worker cooperatives. The goal was to re-examine the relationship between the two movements by taking stock of recent initiatives around the world. To be sure, the relationship between trade unions and cooperatives is as long as the history of trade unions. In fact, it is fair to say that the first associations of workers that emerged in Europe looked more like cooperatives than trade unions.
https://www.ilo.org/global/topics/cooperatives/areas-of-work/WCMS_234174/lang–en/index.htm